Switch



Aug. 14, 1951 l E. H. PITNEY 2,564,229

SWITCH Filed May 15, 1946 Y 3 Sheets-Sheet l 6 mVENroR. EARL H P/TNEY Fla. 3 BY ATT/)RNE Y Aug. 14, 1951 n E; H. PITNEY 2,564,229

SWITCH Filed May 15, 1946 3 Sheets-Sheet 2 FIGLI!-l FI G 8 INVENTOR.

EARL D/TNEY BY fs. MQW

ATTORNE Y Aug. 14, 1951 E. H. PITNEY SWITCH Filed May 15, 1946 3 Sheets-Sheet 5 niunnnnunn OOOOOOQFYAb/ooooooooo o o o O o .o o o o o o o o o o o o Q o o 44 OOoooooooooooooo 47 Q o o o o o o o o o o o o o 0.o. o o o 1# u was 11 151W 15910151; 1511153 111W 43 145 M6 |43 IE5 INVENTOR. EARL H, P/TNEY 9| |49 BY ATTORNEY Patented ug. 14, 1951 UNITED STATES. garant orifice VSWITCH EarrH'Pitney, Minneapolis, Minn. Application Mayas, 1946, serial No. 669,803

This invention presentsv a .mechanism -ior.. selectively closing and opening electric circuits which hasbeen devised to be especiallynseful as a station. selector for radio receivers.` y Y Anobject of the invention is `to provide .amechanism for closing and openingelectric.circuits which will be of novel and improved. construction.

A further object is to provide a. station selector for radio receivers wherein willbefincorporated various desirable and improved. features and characteristics ofy construction .novelvboth .as individual entities of said selector and in combination with each other.

A further object is to provide a station selector for'radio-vreceivers which canbe constituted as an entity adapted to 4be associated in noveland improved manner With radio receivers ncwof commerce. l

And a further object is to provide a station selecting mechanism for radio receivers as hereinafter set forth.

WithI -the above objects in View, as Well as others which will appear as the specification proceeds, the invention comprises the construction, arrangement andcombination of parts kas `now to loe-fully described and as hereinafter-tovbespecifically claimed, itbeing understood that the disclosure herein is merely illustrative and intended in no Way in a limiting sense,-changes in ydetails of construction and arrangement of `parts beingfpermissible so long asfwithin the spirit of the invention and the scope of the claims which follow.

In the accompanying drawings forming'a-.part of this specification, v

Fig. 1 isa perspective view dsclosingaradio receiver anda station selector, or mechanism for. selectively closing andl opening `electric circuits, made according tothe invention and associated with said radio receiver;

kFig. 2 .is a block diagram disclosing the .basic circuit of a superheterodyne radio .receiver and also disclosing circuits of the station selector of the invention associated With'said basiecircuit;

Fig. 3 is an enlarged vertical longitudinal sec.- tional view of the station selector. of Fig. l, .taken asion line 3--3 in Fig. 4,.parts :being omitted;.

Fig. 4 is a horizontal longitudinal sectional view, taken as on line 4 4 in Fig. 3, parts being omitted;

Fig. 5 is an enlarged detail.sectiona1.view,.taken as on line 5-5 in Fig. 4;

Fig. 6 is a detail sectional view, taken Vas-von klinev 6-1-6 inFig. 5;

4 Claims. (Cl.V 20G-46) Fig. 7 is an enlarged plan view of airagment of a continuous or endless tape ofthe station selector;

Fig. 3 .is a detail sectional View of the continuous or endless tape disclosing the manner ofremovably assembling stop plugs or members with said tape; and

Fig. 9 is a Wiring' diagram of circuits of a station selector incorporating features andcharacteristics of the invention.

The station selector herein illustrated and dscribed can Vbe employed in connectionwith any type of radio receiver. ln Fig. 2.0i :thedrawings a radio receiver consisting of. an antennaY Il), a frequency convertor ii, a high frequency oscil lator i2, an intermediate frequency ampli'lerul, a second detector' ifa, an audio amplier |5`and a speaker IG is disclosed. Also in y.said Fig. 2 are disclosed circuits of the station selectorof the invention, including an .antennav I', aLirequency convertor iS and a highfrequency oscillator I9.A

Parts of the radio receiver shown in Fig..2 are housed in a rectilinear box whichis designated 2B in Fig.. l. A turn button 2| adjacent said-rectilinear box 2@ is for adjusting the radio receiver to.off,V automatic or manualv position, fa usual turn buttonr' is for tuningin the `radio receiver when the turn button 2l 'is in manual position, and a usual turn button .23 is for .controlling volume ci saidradio receiver.

Parts of the station selector shown-iin. .said Fig. 2 are housed in a rectilinear Vbox indicated 24 in Fig. 4, and said rectilinear box 24 is'housed in a larger rectilinear box, indicated 25, Which also contains additional elements .of .said station selector.`

The rectilinear box 25 includes a base Wall k26, end Walls 21.27, side Walls 2li, 23 Tand an upper Wall 2S. The upper Wall '29 hingedly supports an L-piece 30, constituted as a part 'of said upper Wall and a part of a side wall ZSjada'ptedtobe swung to open position. thus to aiord access Yto the interior oisaid rectilinear box 25.

A continuous or endless tape Si of anyfmaterial suitable to its purpose is supported 'upon and ridable over idler .pulleys 32 which are in turn mounted upon a frame 33 suitablyand conveniently supported within the rectilinear box '25. The continuous or endless tape 3 I is suitably and conveniently tensioned, as 'oycoil springs 3'4"'attached to .said rectilinear box 25 and to some of the idler pulleys 32.'

Said continuous or endless tape 3|' alsorides upon a driven feed-pulley 35,` and said driven material and a head of solid material.

feed pulley includes two spaced apart sets of spaced apart feed pins 36. The feed pins 36 of each set are adapted to enter spaced apart feed perforations 31 adjacent each of the opposite side edges of the continuous or endless tape 3|. The driven feed pulley 35 is xedly supported upon a horizontal shaft 38 which is suitably and conveniently rotatably mounted upon the frame 33 and rlxedly carries a large gear 39` A synchronous motor 40, suitably and conveniently supported within the rectilinear box 25 and adapted to be energized from any desired source (not shown), includes a driven shaft xedly supporting a pinion 4| which meshes with teeth 42 upon the periphery of the large gear 39.

The construction and arrangement will be such that the driven shaft of the synchronous motor will make one complete revolution per quarter hour to cause the large gear 39 to make one full revolution in four hours, the driven feed pulley 35 to make one-sixteenth of a revolution each quarter hour, and each transverse line along the length of the continuous or endless tape 3| to accomplish one complete cycle of operation in 168 hours, or one week.

In the disclosure as made, the continuous or endless tape 3| includes spaced apart, transversely extending openings in longitudinally extending rows, denoted 43, 44, 45 and 46, respectively, of equally spaced openings. All of the spaced openings in each of the different longitudinally extending rows 43, 44, 45 and 46 are in aligned relation along the length of the continuous or endless tape 3|.

Stop plugs or members 41 are adapted to be removably received in selected ones of the openings of the rows 43, 44, 45, 46 of openings. As will be clear from Fig. 8, each of the stop plugs or members 41 can consist of a shank of stretchable As disclosed at the left in said Fig. 8, the shank of the stop plug or member there shown has been stretched lengthwise thus to be easily insertable in the corresponding tape opening. As disclosed at the right in Fig. 8, the shank of the stop plug or member there shown has been released thus to become expanded and rigidly fastened in the corresponding tape opening. Stated otherwise, the Shanks of the stop plugs or members 41 are adapted to be inserted in the tape openings while stretched lengthwise, and released when fully inserted thus to become securely though removably fastened in said tape openings.

The frame 33 pivotally supports, as at 48, an upper arm 49 and lower arms, designated 50, 5I, 52 and 53, respectively. In turn, said upper arm 49 supports an insulating panel 54 having spaced apart rows, indicated 55, 56, 51 and 58, respectively, of contact elements, and said lower arms 50, 5|, 52 and 53 support insulating panels represented 59, 60, 6| and 62, respectively, each of which supports a row, designated 63, 64, 65 and 66, respectively, of contact elements. The rows 63 and 55, 64 and 56, 65 and 51, 66 and 58, respectively, of contact elements are in vertical alinement.

The construction and arrangement are such that the upper arm 49 is movable upon the pivotal support 48 toward and away from the lower arms 50, 5|, 52 and 5,3, and that said lower arms 50, 5|, 52 and 53 are independently movable upon said pivotal support toward and away from said upper arm 49. The construction and arrangement also are such that corresponding contact elements 4of the rows 63, 55 and 64, 56 and 65,

51 and 66, 58, respectively, can become engaged and disengaged. More explicitly, the row 63 of contact elements includes contact elements denoted 61, 68, 69 and 10 adapted to be engaged with and disengaged from contact elements indicated 1|, 12, 13 and 14, respectively, of the row 55 of contact elements, the row 64 of Contact elements includes contact elements denoted 15, 16, 11 and 18 adapted to be engaged with and disengaged from contact elements indicated 19, 80, 8l and 82, respectively, of the row 56 of contact elements, the row 65 of contact elements includes contact elements denoted 83, 84, and 86 adapted to be engaged with and disengaged from contact elements indicated 81, 88, 89 and 90, respectively, of the row 51 of contact elements, and the row 66 of contact elements includes contact elements denoted 9| and 92 adapted to be engaged with and disengaged from contact elements indicated 93 and'94, respectively, of the row 58 of contact elements. 'I'he contact elements 1|, 19, 81 and 12, 80, 88 and 13, 8|, 89 and 14, 82,90 and 93. 94 and 68, 69 and 16, 11 and 84, 85, respectively, are connected together.

The driven shaft of the synchronous motor 40, which is adapted to make a complete revolution each -quarter hour and xedly supports the pinion 4| which meshes with the large gear 39, also xedly supports a cam member 95 in adjacent relation to said pinion 4| -and cam members, denoted 96, 91, 98 and 99, respectively, adjacent to the cam member 95 and spaced apart along the length of said synchronous motor driven shaft.

The lower arms 50, 5I, 52 and 53 rigidly support extensions, indicated |00, |0I, |02 and |03,

respectively, which project from said lower arms in direction toward the cam members and away from the pivotal support 48, and said extensions |00, IOI, |02 and |03 fxedly support selector elements, designated |04, |05, |06 and |01, respectively, adapted to cooperate in the actuation of the insulating panels 59, 60, 6i and 62 and their rows 63, 64, 65 and 66 of contact elements. In the disclosure as made, each of the selector elements includes a lower feeler pin |08 and an upper retainer lug |09. The feeler pins |08 of the selector elements |04, |05, |06 and |01, respectively, are in alinement with the openings of the rows 43, 44, 45 and 46 of openings in the continuous or endless tape 3|, and the retainer lugs |09 of said selector elements |04, |05, |06 and |01, respectively, are adapted to be trapped by and released from the cam members 96, 91, 98 and 99 in a manner to be made plain.

Each of said cam members 96, 91, 98 and 99 includes an interior surface ||0 of part-cylindrical configuration in concentric relation to the motor shaft upon and over which the retainer lug |09 of the corresponding selector element is adapted to ride, and each cam member 96, 91, 98 and 99 also includes a gap or clearance III at one of its sides of width to allow passage of the corresponding retainer lug |09. One end of the part-cylindrical surface I|0 of each of the cam members 96, 91, 98 and 99 terminates at one side of the gap or clearance I I I and the other end of the part-cylindrical surface I I0 of each cam member 96, 91, 98 and 99 merges in an interior cam surface I I2 which curves smoothly outwardly and terminates at the opposite side of said gap or clearance I.

The cam member 95 includes an exterior surface I|3 of part-cylindrical coniguration in concentric relation to the motor shaft, a drop-off portion I I4 and an exterior cam surface I I5 which assises 'curves lslnothligfoutwardly from the interior end .insulating panel 54, includes a foot-portion- II-'I ridableupon the exterior surfaces I I3 and `1| |5 of the cam 95;

Connecting posts Vbetween the insulating Ypanel 54 andthe insulatingnpanels 59360,' 6 I and'62 are denoted vI|'8;QI I9, I20and 12|, respectively;v Each of said 'connecting posts has its lower end-rigidly connected to an insulating panel,59,-60, 6| or `62, as `the case maybe-,and its body portion-slidably arranged `in an opening in' the-insulating panel 54.. `A head upon each connecting-post is adapted to become engaged with the upper -surfaceof said insulatingV panel '54thus to Ylimit the extent ytowhich' the insulating Vpanels* 59, 60 6 I and-62 can be moved in direction'awayvfrom- -therinsulating panel.

The gaps or clearances I I'I 4of the different cam members, y9T, 98 and 99 "are in `alinementfin direction longitudinallyof the driven shaftofthe synchronousA motor 40 :and lthe just mentioned cam` members and the cam member 95 obviously are .adapted to make one complete revoluti'oneach quarter hour. The construction and Yarrangement will be `such that the openings of the different` rows43, 44, 45, 46 of openings in the conpins|08 inresponse. to advancement ofsaid con.-

tinuous .or-endless tape, and the construction and arrangement also will be suchthat each of the gaps or clearancesv will ,become situated substantially invertical -alinement `with each opening ofA the correspondingrow of ,openings as the `.openings successively become situated direct.- ly below the. motor shaft about as disclosed in Figg of the drawings.V

In said Fig. 5, the feeler pin I 08 of. the.. selector element .|04 is yrestingupon a stop ,plug or member. 4l in.an opening of the-row 43 of openings and the-feeler pins |08 of the selector elements |05f..-|06;-and, |01 are situated in openings of the rows 44,45 and 46, respectively, of openings. The retainer Ylug |09 of said selector element |04 isat elevationjust above the free end of the interior cam surface I I2 of the cam memberS and alined withsaid mentioned interior cam surface ||2, and thevretainer lugs |09 of the/selector elements |05, |06 and |01 are situated `at elevation below the free ends of the interior cam surfaces I|2 `of the cam members 91, 98 and 99. The contact elements of the rows 55, 63 of contact elements are interengaged inFig. 5 and the head of the .conmeeting IDOSt.` I I 8 is in spaced relation to the upper surface of the insulatingr panel 54. The contact elements of the rows 56,64 and 51, 65 vand 58, 66 are-disengaged in said Fig. 5, and ,the heads of the, connecting posts I I9, |20 and I2| are engaged againsttheupper surface of said insulating panel 54.` The foot -portion I I1 of the supporting bracket IIS is disclosedin Fig. 5 as having just dropped off of the cylindrical surface ||3 of the cam member 95.

Supposingthe parts of the new and improved mechanism to be situated as in Fig. 5 of the drawings and the synchronous motor shaft to be driven ahead to advance .the cam members 85, 96, 97, 98 and 99 inthe direction of the arrow in said Fig. 5, the cam surface |I2 of the cam member 96 will become vengaged Ibeneath VA-the `'retainer -lug |09 -of the selector element |04 thus to cause-said selector element 104' to betrapped With furtheradvancement of said cammember 96, said'retainer lug |09 of said selector element |04 -will become elevatedfuntil -thevforward portion of the cylihdrical surface I0 of the cam member 96 vreaches the location of the retainer llug of the selector element |04,^and said-selector element |04 will remain trapped by'said'cammember 96-unti1 the cam members have beenV returned to their -positions as in 'said Fig. 5. At rsuch time, the vnext succeeding opening in the row 43 of openings will be beneath the selector 'element |04 andsaid selector element will become released to be moved dovvnward'by gravity. If -said next succeeding opening of row 43 of openings has no stop plug or member 4l,'the feeler pin |08 of the selector element |04 will enter sad next succeeding open'- ing, but if the opening mentioned contains a stop plug or member 47, the feeler pin of said selector element |04 will engage .said stop-plug or `qmem- Aber to cause the selector element to be situated Yas in Fig. 5. With'advancement of the cam mem'- 4ber. 95 the cam surface II5`will ride under the foot portion I|`I ofthe supporting bracket |I6 thus to cause the insulating panel '54 to be elevated. At this same time, however, the interior cam surface I I2 'of the cam member 96 will cause the insulating panel 59to be elevated an equal amount, or tothe same degree, thus to cause the contact elements of rows 55 and 63 of contact elements to remain engaged.' The construction and arrangement will. be such thatwhen the exterior cylindrical surface I3 of the cam member commences to. ride under the foot portion I7 as the. camsurface i5 rides from under said foot portion, the interior cylindrical vsurface |I`0 'of a cam member 96, 97., 98 or 99, as the case may be, willcominenceV to ride under the retainer lug |09 of the corresponding selector element as. the cam surface |I.2 rides from-under the retainer lug-of said selector element. Stated otherwise, the construction and arrangement will be such that rows 55',- 63- or 56.. 64 or 51.65 .or 58, 66 of` contact ele.- mcnts caused to become engaged because ofthe feeler pin|98 ofthe corresponding .selector element .becoming ,engagedlagainst a stop plug -or member 47,1'as the rows A55, 63 of Contact elements are disclosedin Fig. 5 'of the drawings, will remain engaged for the whole of a quarter hour. The exterior cylindrical surface I I3 willpass from under the ,footportion' I1 at; thesameinstant that the -interiorcylindrical surface YI I0 passesl from under the supporting bracket I I6 to .cause the insulating panell54 to be elevated, any feeler vpins |08 in openings in the continuous or endless tape in said Fig. 5 lwi-ll be removedffrom said tape through the instrumentality of the corresponding connecting posts, as will be obvious. That is to say, the heads of the connecting pestsv engaged with the insulating panel-54 in Fig. 5 will be elevated in response to eleva-tion of said insulatingpanel 54, thus to cause the ,insulating panels which are rigid with said connecting posts to be elevated and the feeler pins|08 of the correspondingselector elements tobecome removed from the tape openings. Feel'- er vpins removed from tape openings will be held above .the tape until the foot portion ,I i? falls `from the drop-off vI I4' and will then drop either to enter other openings or to engage stop plugs or members fili, as the case may be.

In Fig. 9 of the drawings, 122 denotes a loop antenna, 123 indicates a high frequency oscillator coil, 124 designates a pentagrid convertor tube including a heater E25, and 26 represents a radio frequency choke, Pretuned variable condensers are designated 121, 1'26, 29, i35, 131 and i352.

An intermediate signal conducting connection 13 3 extends to the loop antenna 122, a conducting connection i3d extends from said loop antenna to a grid of thefconvertor tube 124, and an intermediate s-gnal conducting connection 135 extends from said convertor tube.

The radio frequency choke 126 is connected between the conducting connection 135 and grids of the convertor tube 124, as well as between the conducting connection 133 and said conducting connection 135.

A conducting connection E36 extends from the 4conducting connection i254 to the contact element 96, conducting connections 31 extend from the conducting connection 133 to each ofthe variable oondensers 121, 123, 12', 13%, i31 and 132, and

conducting connections, denoted 138, 39, 149, v

141, 1132 and 143, respectively, extend from said variable condensers to the contact elements 1G. 18,811,151, 15 and 83.

The high frequency oscillator coil 123 is connected between the conducting connection 1355 and a grid of the convertor tube 124, as well as between said' conducting connection $33 and the radio frequency choke 126.

Conducting connections to the heater 125 are denoted 144 and 145, and power circuit conducting connections to the Contact elements 12 and 13 are indicated 146 and 141, respectively.

The contact elements 91 and 92 are included in a circuit also including a motor 148 adapted to be energized by a battery 149.

The circuits included in Fig. 9 of the drawings also incorporate resistances, fixed condensers, etc., which are requisite to the proper and intended functioning of said circuits. l

The mechanism as herein illustrated and described is adapted to be capable of selecting any desired one of three different radio stations to which the radio receiver disclosed is to be tuned, and said mechanism also is capable of selectively causing the circuit including the motor 148 to be f closed and opened. It will be apparent that the r'embodiment of the mechanism selected for illustration and description is adapted to be set up for operations each continuing for a quarter hour interval throughout a period of a week, and that at the end of a weeks performance the operations of said mechanism will be repeated.

A stop lug or member 41 inany opening of row 43 of openings is adapted to cause the contact elements of rows 55 and 63 of contact elements to be interengaged and held interengaged for a quarter hour, in the manner as hereinbefore set forth, and interengagement of said rows 55 and 63 of contact elements will cause one of the several radio stations which are capable of `being selected, say radio station A, to be tuned into the radio receiver. The selection of radio station A obviously will be a function of tank circuits of Fig. 9 of the drawings including the loop antenna 122, the pretuned variable condenser 121, the high frequency oscillator coil 123, the pretuned variable condenser 131i, etc. Stated otherwise, tank circuits of said Fig. 9 adapted to be closed when the rows 55 and 63 of contact elements become interengaged include variable condensers 121 and 13B so pretuned as to cause a particular value adapted to select the frequency emanating from said radio station A to be resonated and the audio signal received to be imparted to the intermediate frequency amplifier of the radio receiver.

A stop plug or member 41 in any vopening of row 44 of openings is adapted to cause lthe contact elements of rows 56 and 64 of contact elements to be interengaged for a quarter hour, and interengagement of said rows 56 and 64 Will cause a different one of the radio stations, say radio station B, to be tuned in. The selection of radio stationB will be a function of tank circuits including the loop antenna 122', the pretuned variable condenser 126, the high frequency oscillator coil |23,- the pretuned variable condenser 131, etc. That is to say, tank circuits adapted to be closed when the rows 56 and 64 of contact elements become interengaged include variable `condensers 128 and 131 so pretuned as to cause a particular value adapted to select the frequency emanating from said radio station B to be resonated and the audio signal received to be imparted to the intermediate frequency amplifier of the radio receiver.

A stop plug or member 41 in any opening of row 45 of openings is adapted to cause the contact elements of rows 51 and 65 of contact elements to be interengaged for a quarter hour, and interengagement of said rows 51 and 65 will'cause a yet diiferent one of the radio stations, say radio station C, to be tuned in. The selection of radio station C will be a function of tank circuits including the loop antenna 122, the pretuned variable condenser 129, the high frequency oscillator coil 123, the pretuned variable condenser 132, etc. Put differently, tank circuits adapted to be closed when the rows 51 and 65 of contact elements become interengaged include variable condensers 129 and 132 so pretuned as to cause a particular value adapted to select the frequency emanating from said radio station C to be resonated and the audio signal received to be imparted to the intermediate frequency amplier of the radio receiver.

It will be evident that the continuous or endless tape 31 could include additional rows, such as 43, 44, 45, of openings adapted to receive stop plugs or members, such as 41, for causing other tank circuits including pretuned variable condensers, such as 121, 130 and128,131and129, 132, to be closed and opened, thus to cause additional radio stations to be selectively tuned in.

A stop plug or member 41 in any opening of row 46 of openings is adapted' to cause the contact elements of rows 58 and 65 of contact elements to be interengaged for a quarter hour, and interengagement of said rows 58 and 65 will cause the circuit including the motor 148 to be closed. Said motor 148 can be employedfor any desired purpose, as, for instance, to actuate or drive a phono graph.

with and disengaged from said upper contact element, a supporting member rigid with said upper contact element, a selector element rigid with said lower contact element and having a retainer element, a rst cam member ridable beneath said supporting member including an exterior part-cylindrical surface, a drop-off portion extending interiorly from said exterior partcylindrical surface and an exterior cam surface curving smoothly outwardly from the interior end of said drop-off portion and merging in said exterior part-cylindrical surface, and a second cam member for trapping and releasing said retainer element including an interior partcylindrical surface in concentric relation to said exterior part-cylindrical surface, there being a clearance situated opposite said drop-off portion and an interior cam surface opposite said eX- terior cam surface curving smoothly outwardly from said interior part-cylindrical surface and terminating at said clearance.

2. In a mechanism for selectively closing and opening electric circuits, an upper contact element mounted for movement in vertical direction, a lower contact element mounted for movement in vertical direction adapted to be engaged with and disengaged from said upper contact element, a supporting member rigid with said vupper contact element, a selector element rigid with said lower contact element and having a feeler pin and a retainer element, a rst cam member ridable beneath said supporting mem ber including an exterior part-cylindrical surface, a drop-off portion extending interiorly from said part-cylindrical surface and an exterior cam surface curving smoothly outwardly from the interior end of said drop-off portion and merging in said exterior part-cylindrical surface, a second cam member for trapping and releasing said retainer element including an interior part-cylindrical surface in concentric relation to said exterior part-cylindrical surface, there being a clearance situated opposite said drop-off portion and an interior cam surface opposite said exterior cam surface curving smoothly outwardly from said interior partcylindrical surface and terminating at said clearance, a member having spaced apart openings adapted to removably receive stop members, means for feeding said member to cause said spaced apart openings to be successively situated beneath said feeler pin, and a connecting post between said upper and lower contact elements rigid with the lower contact element and slidable relative to the upper Contact element.

3. In a mechanism for selectively closing and opening electric circuits, an upper contact element mounted for movement in vertical direction, a lower contact element mounted for movement in vertical direction adapted to be engaged with and disengaged from said upper contact element, a supporting member rigid with said upper contact element, a selector element rigid with said lower contact element and having a retainer element, a first cam ridable beneath said supporting member including an exterior part-cylindrical surface, a drop-off portion extending interiorly from said exterior part-cylindrical surface and an exterior cam surface curving outwardly from the interior end of said dropoif portion and merging in said exterior partcylindrical surface, and a second cam member for trapping and releasing said retainer element including an interior part-cylindrical surface in concentric relation to said exterior part-cylim drical surface and an interior cam surface opposite said exterior cam surface curving outwardly from said interior part-cylindrical surface and terminating at a clearance situated opposite said drop-off portion.

4. In a mechanism for selectively closing and opening electric circuits, an upper contact element mounted for movement in vertical direction, a lower contact element mounted for movement in vertical direction adapted to be engaged with and disengaged from said upper contact element, a supporting member rigid with said upper contact element, a selector element rigid with said lower contact element and having a feeler pin anda retainer element, a rst cam member ridable beneath said supporting member including an exterior part-cylindrical surface, a drop-off portion extending interiorly from said part-cylindrical surface and an exterior cam surface curving outwardly from the interior end of said drop-off portion and merging in said exterior part-cylindrical surface, a second cam member for trapping and releasing said retainer element including an interior partcylindrical surface in concentric relation to said exterior part-cylindrical surface and an interior cam surface opposite said exterior cam surface curving outwardly from said interior part-cylindrical surface and terminating at a clearance situated opposite said drop-off portion, a member having spaced apart openings adapted to receive stop members, means for feeding said member to cause said spaced apart openings to be successively situated beneath said feeler pin, and connecting means between said upper and lower contact elements rigid with one of the contact elements and movably assembled with the other contact element.

EARL H. PIINEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 395,781 Hollerith Jan. 8, 1880 1,684,394 Haase Sept. 18, 1928 1,726,622 Holden Sept. 3, 1929 1,803,111 Harter Apr. 28, 1931 1,962,335 Wensley June 12, 1934 1,978,967 Sprague Oct. 30, 1934 2,098,359 Reynolds Nov. 9, 1937 2,166,691 Pare July 18, 1939 2,229,100 Lapsley Jan. 21, 1941 2,257,537 Samburg Sept. 30, 1941 2,324,221 Luhn July 13, 1943 2,345,289 Reiber Mar. 28, 1944 2,367,363 M att Jan. 16, 1945 

